Fiberglass Pipe Research Articles

Forecasting and characterization of composite pipeline based on experimental modal analysis and YUKI-gradient boosting

The surging demand for fiberglass pipe materials in the Oil and Gas transportation sectors are driven by their exceptional durability and ease of use. This study combined improved experimental and numerical analyses to assess the behavior of composite pipe and focused on characterizing it, especially in terms of identifying the frequency based on different crack lengths. Various tests, such as impact hammer tests and modal analysis, determine the pipe properties and natural frequencies. The study also investigates the impact of varying fiber volume fractions to refine material properties. To understand crack effects behavior, different crack lengths have been introduced into the pipes and analyzing the modal analysis using frequency and mode shapes. The effect of cracks into frequency based on experimental and developed numerical models is investigated. A predective model is developed based on YUKI-Gradient Boosting algorithms and Deep Artificial Neural Networks. To test the robustness of developed algorithm several tests are provided and the results show the effectiveness of YUKI-Gradient Boosting outperforms YUKI-Deep-ANN in accuracy and consistency.

Application of fiberglass pipes in geothermal circulation systems

The results of calculating the coefficient of thermal conductivity of the developed construction of the pipeline from multilayer composite spatially oriented fiberglass are given. A method of calculating the coefficient of thermal conductivity of a pipe wall with a complex structure of reinforcement has been developed. The fiberglass pipe is made by the continuous method of oblique-layer longitudinal-transverse winding on a self-feeding frame of reinforcing pseudo-tape moistened with a binder in the form of a rarefied mesh. With each rotation of the mandrel, it shifts by the amount of hardening of the obtained two-component material under the influence of temperature. A comparison of calculated and experimental data was made. When comparing various known calculated dependencies and experimental values, the accepted physical model and the real structure of the material are determined. The known dependences obtained for a medium with infinite long parallel cylindrical inclusions for unidirectional and orthogonally reinforced materials and therefore for materials with a complex structure and scheme of reinforcements give errors and deviations. The work assumes that fiberglass consists of two components - a reinforcing filler and a binder with pores, the reinforcing fibers are endless and have a circular cross-section, the reinforcing fibers are evenly distributed in the matrix of the binder, there is an ideal thermal contact at the boundaries of the distribution between the reinforcement and the binder. Experimental data on determining the transverse thermal conductivity of unidirectional fiberglass rods with reinforcement based on aluminoborosilicate or magnesium-aluminosilicate glass and epoxy binders showed the smallest error in comparison with the calculated ones (8-10%). They investigated the fact that the coefficient of thermal conductivity of a fiberglass pipe is 100 times lower than that of a steel pipe. It was determined that it is possible to replace a steel pipe with a diameter of 219 mm with a fiberglass pipe with a diameter of 146 mm.

OPTIMIZATION IN THE RECONSTRUCTION OF THE RESERVOIR PRESSURE MAINTENANCE SYSTEM (RPMS) USING SIMULATION MODELING

The paper considers the optimization of reservoir pressure maintenance systems using simulation methods. The main goal is to consider the impact of various technological indicators on capital and operating costs. The initial parameters for calculating optimization options are the cost of electricity and the density of the injected water; fiberglass pipes (SPT-80, SPT -100) are used as pipes, the wall roughness of which is assumed to be 0.015 mm.The costs of capital construction during the reconstruction of pipelines and the pumping unit, as well as operating costs for overcoming hydraulic losses in pipelines, in well piping and for energy losses of pumping units are calculated. When calculating, special attention is paid to losses that make up 90% of the total power losses in the pressure maintenance system, such as power losses associated with imperfect pump design; power losses for choke of injection wells; losses of electricity for the operation of pipelines.The results are presented on the example of a small cluster pumping station. 4 options for optimizing calculated in terms of capital and operating costs for three main points are presented: pumping equipment, pipelines and wells. To assess the impact on production, a reservoir model was built using the material balance method. It should be noted that synthetic data were used for this case, because in reality, this CPS is just a part of the pressure maintenance system.When optimizing 20 facilities, the following results were obtained: on average, over 20 years, the difference in operating and capital costs between the basic reconstruction option and the most profitable reconstruction option with optimization is about 350 million rubles.

Абразивная износостойкость и ресурс эксплуатации труб из стеклокомпозита

This article presents studies of the abrasive wear resistance of fiber-glass composite pipes inner surface, which are laid us-ing microtunneling technology under construction of drinking water pipes, irrigation and sewerage systems. Due to a very smooth inner surface, the pipes have a high coefficient of fluid flow speed transmission through the pipe and a low coeffi-cient of roughness. When in long-term operation, the movement of water and solid particles through the pipeline eventually causes wear of inner walls of the pipe. The study of data on abrasive wear and abrasive resistance of fiber-glass composite pipes allows calculating the pipeline's operability under controlled conditions, predicting the period of trouble-free opera-tion of pipelines and making a reasonable choice of material for pipeline manufacturing. The objects of the study of glass composite pipes samples were selected, manufactured by LLC «New Pipe Technologies» using the method of continuous winding with an inner layer based on: orthophthalic polyester, isophthalic polyester and vinyl ester resins. The assessment of the overall wear resistance of the inner surface of the pipes was fulfilled using test equipment according to the Darmstadt method (GOST R 55877-2013, method B). This method allows simulating the abrasion and wear of linings and pipes that may occur in real operating conditions. Crushed quartz was used as an abrasive material. According to the results of the research, the arithmetic mean values of wear and safety coefficients of fiber-glass composite pipes were deter-mined depending on the number of test cycles. The data were used to select the most promising material as a polymer matrix for the production of fiberglass pipes both for water supply and sewerage.

Estimation of the Possibility of Application of Polymer-Composite Materials in Oil Field Equipment under Abrasive Action

Currently, composites with a polymer matrix are most widely used in various industries, including the oil and gas sector, as an alternative to traditional metal materials. The most widespread of non-metallic pipes in the Russian Federation are pipelines made of fiberglass. One of the clear advantages of polymeric materials over metal products is their corrosion resistance. At the same time, upon contact with liquids containing abrasive particles, composites with a polymer matrix can degrade with varying degrees of intensity. Such as type of degradation like hydroabrasive wear of pipelines is common and can lead to equipment failure. Various linings are applied to the inner surface of fiberglass pipes to minimize hydroabrasive wear. This study attempts to assess the durability of coated and uncoated composite polymer materials under conditions of hydroabrasive wear, as well as to compare the properties with other materials currently used in industry.

The impact of complex engineering and geological conditions on the durability of the polymer pipeline

Formulation of the problem. During the construction of the oil collector, in order to ensure uninterrupted transportation of products, it was planned to lay an industrial oil collector made of fiberglass pipes. In some areas, repeated depressurization of the joints of the fiberglass oil collector occurred. In this regard, there was a need for a comprehensive approach to establishing the causes of the aerial situations. The purpose of the article is to analyze the impact of complex engineering and geological conditions on the durability of the polymer pipeline using the example of an industrial oil collector made of fiberglass pipes of the Anastasiv deposit, located in the territory of the Romen district of the Sumy region of Ukraine. Materials and methods. To achieve the goal, a visual survey of the geological and geomorphological structure was performed, as well as the analysis of the engineering and geological conditions of the territory where the fiberglass pipeline is laid. Soil samples were taken from the place of depressurization of the polymer pipeline joint, and their physical and mechanical characteristics were determined. Modeling and calculation of the stability of the slope on which the depressurization of the joint of the polymer pipeline occurs, were carried out by the finite element method. Results. During the examination of the fiberglass pipeline, negative and potentially negative factors of the engineering and geological conditions influence on the laying and operation of fiberglass collectors were established. It was revealed that there was a discrepancy between the design decision and the actual layout of the fiberglass pipes, which could lead to the occurance of areas of "sag" and, as a result, an increase in the stresses in the pipeline from the backfill load. At the same time, the realization of subsidence phenomena of IGE 5 after laying the pipeline also led to additional non-design stresses. The analysis of engineering-geological and hydrogeological conditions indicates the possible activity of slope processes in the study area, which leads to a violation of the stability of the slope and, consequently, the occurrence of additional displacement and stresses due to,deformation of the soil massif. Scientific novelty and practical significance. The necessity of conducting engineering-geological surveys to assess the impact of complex engineering and geological conditions on the durability of a polymer pipeline is substantiated. The main negative processes and phenomena that led to emergency situations on the territory of laying the polymer pipeline were identified.

Design and manufacture of Fiberglass Pipe Cutting Machine with Adjustable Holder

Fiberglass is a material that is used for several products. This material was chosen because it has many advantages compared to other materials, namely it has better resistance, relatively affordable production costs and is easy to shape. PT.X is one of the manufacturing companies engaged in fiberglass, namely the manufacture of pipes and body from vehicles. In this case study the company still uses hand milling and manual processing. Fiberglass pipe in this company is molded indirectly to the size requested by the customer, therefore a cutting process is needed to get the required pipe length. The blade used specifically is a diamond-coated cutting blade because the fiber material is not heat-resistant. In this research, the researcher wants to design a fiberglass pipe cutting machine with an adjustable holder that can be adjusted so that it can cut various pipe sizes. Making the design of this machine is done using Fusion 360 software. The making of the machine includes the cutting process, grinding process, and welding process. The machine can cut a pipe with a diameter of 100 mm in 20 seconds and for a pipe with a diameter of 500 mm in 1 minute 20 seconds.

Probability Analysis of Human Error in The Fiberglass Pipe Installation Process with Spar-H And FTA Methods at PT. GFRP

Probability Analysis of Human Error in The Fiberglass Pipe Installation Process with Spar-H And FTA Methods at PT. GFRP

Investigating the influence of the diameter of a fiberglass pipe on the deformed state of railroad transportation structure "embankment-pipe"

This paper has analyzed the use of fiberglass pipes in the body of the railroad embankment by a method of pushing them through the subgrade. A flat rod model has been improved for assessing the deformed state of the transport structure "embankment-fiberglass pipe" by a method of forces when replacing the cross-section of the pipe with a polygonal one. The analytical model accounts for the interaction between the pipe and soil of the railroad embankment. To this end, radial and tangential elastic ligaments are introduced into the estimation scheme, which make it possible to simulate elastic soil pressure, as well as friction forces that occur when the soil comes into contact with the pipe. The deformed state of the transport structure "embankment-fiberglass pipe" was calculated by the method of forces and by a finite-element method under the action of load from the railroad rolling stock, taking into consideration the different cross-sections of the pipe. It has been established that with an increase in the diameter of the fiberglass pipe, the value of deformations of the subgrade and fiberglass pipe increases. With a pipe diameter of 1.0 m, the deformation value in the vaulted pipe is 2.12 mm, and with a pipe diameter of 3.6 m – 4.16 mm. At the same time, the value of deformations of the subgrade under the sleeper is 5.2 mm and 6.0 mm, respectively. It was determined that the maximum deformations of the subgrade, which occur above the pipe, with a pipe diameter of 3.6 m, are 4.46 mm. At the same time, the maximum vertical deformations of a fiberglass pipe arise in the pipe vault and, with a pipe diameter of 3.6 m, are 4.16 mm. It has been established that the maximum horizontal deformations of the subgrade occur at points of horizontal diameter of the fiberglass pipe while the minimal horizontal deformations of the subgrade occur at points lying on the vertical diameter of the pipe

The dependence of the deformation behavior of fiberglass pipes on the initial disorientation of reinforcement subjected to repeated-static internal hydrostatic pressure and axial tension

The problems of influence of the technological reinforcement disorientation on the deformation behavior of composite tubular elements subjected to repeated-static internal hydrostatic pressure and axial tension, as well as the resistance to fracture of these elements subjected to the above-mentioned loading are discussed.The experimental part of research is carried out applying thin-walled tubular elements manufactured from the fiberglass fabric prepreg based on the modified epoxy resin.It is established that a possible deviation of the reinforcement angle from 60 to 80 taking place during the processing of material into goods has little effect on the fracture resistance both subjected to the internal hydrostatic pressure and axial tension of fiberglass pipes manufactured so that the directions of reinforcing fiberglass fabric warp and ones axis are coincided.Meanwhile, the following was stated that the accompanied shearing deformations are arising besides the basic cyclic deformations (noted in the direction of force application) for initially disorientation fiberglass pipes in difference from non-disoriented ones at the condition of pulsating (irregular) loading by the above-mentioned load-bearing factors.Calculations are proved that the reinforcement disorientation direction in the above-underlined limits is brought to the significant decrease of the energy dissipation coefficient of fiberglass pipes.The statement aiming the constructional solution of the problem is formulated in a sense of negative influence of the technological reinforcement disorientation on the composite tubular elements functioning at the conditions of cyclic axial tension and internal hydrostatic pressure.

A modeling of the inertia properties of a drill string section as a continual bent rotating rod

The article considers the problem of determining the moment of inertia of the bent rotating section of the drill string. The tasks of such a plan are of paramount importance for the dynamic analysis of drill strings in rotary and rotaryturbine drilling methods. Presented are the exact and approximate analytical dependences for determining the moment of inertia of the bent section of the drill string, depending on the geometric parameters of its deflection. Given the scientific and practical interest in the use of pipes made of non-traditional materials, the moments of inertia for bent sections of steel, titanium, aluminum and fiberglass drill pipes are calculated. The nature of the change in the moment of inertia of sections of drill pipes of different diameters depending on the length of the half-wave and the magnitude of the maximum deflection is established. Keywords: drill string; rod; moment of inertia; deflection boom; deflection half-wave length.

CALCULATION OF THE CONSTRUCTION OF THE SEWERAGE COLLECTOR DURING ITS REPAIR AND RESTORATION IN AN OPEN WAY

A significant part of sewerage networks in cities in the country are reinforced concrete pipelines with a diameter of 500 to 1500 mm, which lie at a small depth. In many cases, they transport wastewater to treatment plants through areas free of traffic and pedestrians. These factors allow you to effectively perform repair and restoration work in an open way. Corrosion processes that occur in the surface part of the collectors lead to the destruction of the basement. The tray part of the collectors, which is constantly filled with wastewater, remains intact. As studies have shown, the preserved tray part can be successfully used as a fixed formwork and support element in the restoration of the basement of the collector. In this case, to create a new basement part of the collector, in place of the destroyed, it is advisable to use a monolithic structure of polymer concrete reinforced with composite reinforcement. These works are performed using pneumatic and inventory formwork. To implement the proposed structure, it is necessary to perform a preliminary calculation of its load-bearing capacity, provided that it rests on the preserved tray part. As a result of this work it is possible to receive economy in comparison with use for repair and restoration works of polyethylene and fiberglass pipes of necessary diameter. During the calculation, a model of the collector was considered, consisting of a preserved tray part of the collector made of concrete class C12 / 15, the upper part of the collector made of concrete class C20 / 25. The calculation proved the possibility of using polymer concrete structures for repair and restoration of sewers in an open way, provided that the new basement rests on the preserved tray part. The proposed open method allows to significantly reduce the cost of repair and restoration work in comparison with the use of polyethylene and fiberglass pipes.

Hardening condition of unsaturated polyether from alcoholysis products of secondary polyethylene terephthalate

The technological parameters of the curing of unsaturated polyesters synthesized on the basis of alcoholysis products of secondary polyethylene terephthalate and used in the production of fiberglass pipes have been studied. It is shown that unsaturated polyesters synthesized on the basis of alcoholysis products can completely substitute imported resins of 196 and 196A grades in the production of fi berglass pipes.

Fatigue Performance Analysis of GRE Composite Pipes by Conducting Tension-Tension Tests on the Rings Cut from the Pipe

Abstract The main purpose of this study is to analyze the fatigue behavior of an industrial (±55°)9 filament-wound glass reinforced epoxy pipe. Fatigue tests are conducted in accordance with ASTM D2992, Standard Practice for Obtaining Hydrostatic or Pressure Design Basis for Fiberglass (Glass-Fiber-Reinforced Thermosetting-Resin) Pipe and Fittings, but instead of the entire pipe, rings cut from the pipe are used in the tests. This standard proposes a frequency of 0.42 Hz and stress ratio of R = 0.05. Tension-tension fatigue tests are performed on the rings at different load levels from 60 to 90 % of the ultimate hoop strength of the pipe. After the tests, the maximum pressure and maximum hoop stress curves versus the number of cycles to fatigue failure are presented. A comprehensive discussion about the importance of substituting the ring test method with ASTM D2992 standard test methods to determine the long-term performance of the composite pipes in the future is presented. The microscopic fatigue failure mechanisms of the rings are also characterized and interpreted using a scanning electron microscope.

APPLICATION OF PNEUMATIC FORMWORK FOR REPAIR AND RESTORATION OF SEWER PIPELINES USING CLINKER BRICK AND POLYMER CONCRETE

Raising of problem. A significant part of wastewater in Ukrainian cities is discharged using sewer collectors with a diameter of 300 to 1 400 mm, the depth of which is within 3…8 m. A significant part of them is destroyed due to corrosion processes that take place in the surface space. Today, the problem of repair and restoration of sewerage networks is becoming especially relevant in connection with the increased requirements for environmental protection. Failure in sewer lines usually results in wastewater infiltration into groundwater and soil. During the repair and restoration of sewage collectors, open and closed methods of work are used. Taking into account that a significant part of sewage collectors passes through areas where there are no transport arteries, through agricultural land and have an insignificant depth of occurrence, and also the fact that their trough part, as a rule, cannot be destroyed due to corrosion, it is advisable to carry out repair and restoration work on them in an open way. Analysis of accidents on sewage collectors, which took place in different cities of Ukraine, showed that, as a rule, due to corrosion, intensive destruction of the roof of the collectors occurs. At the same time, the trough part of the collectors remains intact due to the fact that it is constantly filled with waste water. When repairing such sections of sewerage networks in recent years, operating organizations have been using polyethylene and fiberglass pipes. These smaller pipes are installed in the retained trough part, thus reducing the network diameter. The cost of new pipes is quite high, which in turn increases operating costs. The use of pneumatic formwork allows you to create a new collector, and as the main bearing element, you can use the saved tray part. 
 Purpose. Evaluation of the possibility of using known materials for the manufacture of pneumatic formwork, which will make it possible to carry out repair work to create a new vault using the trough part of the sewer collector as a supporting structure, which will significantly reduce repair costs compared to using pipes made of polymer materials. 
 Conclusion. The investigated samples of materials – fabric Mare 1400 and Hypolon (ORCA 828) – can be used for the manufacture of pneumatic formwork, since laboratory tests made it possible to conclude that there was no adhesion between concrete and material samples.

ACOUSTIC EMISSION TESTING OF FIBERGLASS PIPES AND FITTINGS

Experimental studies was carried out. The purpose was to develop a method to test fiberglass pipelines in operating mode. The acoustic emission method was chosen as the main method of nondestructive testing, and visual and dimensional inspection was chosen as an additional method. Acoustic parameters and acoustic emission properties of fiberglass pipes were determined. It was found that acoustic emission sensors can be installed at distances of up to 9-18 m from each other. A series of loading tests was carried out to refine the methodology. Every loading case was performed until leakage registration. In most cases, leakage occurred near the fillet at pressures of 2.2…3.0 from the working pressure, which indicates a large margin of safety for fiberglass pipes. It is confirmed that the acoustic emission method allows early defect detection. Based on the acoustic emission data, 4 main stages of fiberglass pipes degradation were identified. Visual and dimensional inspection was informative only at stages III – IV. Stage IV in most cases corresponds to the leakage. Even early stage of depressurization was registered as continuous acoustic emission. Signals with amplitudes exceeding 60…80 dB were registered at all loading stages. The location map became informative after filtering events by acoustic emission parameters. A methodology for the testing of fiberglass pipes and fittings in operating mode was developed. It contains, in contrast to the currently valid standards, specific numerical values of various quantities related to both the preparation and carrying out of acoustic emission testing and the classification of the identified sources of acoustic emission according to the degree of danger and allows to evaluate the residual life of fiberglass pipelines. The most informative parameter was the activity of acoustic emission; therefore, it is recommended to carry out loading without holding the pressure. It is planned to carry out additional experiments to clarify the mechanisms of fracture acting at each of the 4 identified stages of degradation.

AN ALTERNATIVE METHOD FOR CONTROLLING HYDRATE FORMATION IN NATURAL GAS REDUCTION UNIT WITH LIQUEFIED NATURAL GAS PRODUCTION

Background The article is devoted to the problem of controlling gas hydrates formation at a gas pressure reduction station due to the process of natural gas pressure reduction. Aims and Objectives The main aim of the study is to propose the use of fiberglass pipes as a method of controlling gas hydrates formation in the gas reduction line of a natural gas reduction plant with liquefied natural gas production. Comparison of the developed technology for hydrate formation controlling with the control method, originally laid down in the reduction unit under consideration. Ensuring safe work of service personnel, reducing economic costs for the construction and operation of the gas distribution station due to the use of the developed technology controlling gas hydrate formation in the gas reduction line of the reduction unit. Results Modern trends in the introduction of lowtonnage production of liquefied hydrocarbons on the basis of a gas distribution station are considered. The method of hydrate formation controlling in the line of gas reduction unit, originally laid down by the author of the patent, is analyzed, and the conclusion is made that the use of this technology to control gas hydrates is inappropriate from the point of view of the safety of gas distribution station workers. The advantages of fiberglass pipes made of composite materials over steel pipes are established. It is proved that the use of composite gas pipelines as a method of controlling hydrate formation in a reduction unit provides a positive economic effect in the construction and operation of a gas distribution station due to certain advantages of fiberglass pipes over steel pipes. It has been proved that to ensure the safety of the work of the personnel of a gas distribution station operating a natural gas reduction unit with the production of liquefied natural gas, it is advisable to replace steel pipes with fiberglass pipes made of composite materials, instead of using an increase in the energy flow rate and its turbulization to control gas hydrates formation. The percentage of reduction of friction pressure losses in the technological gas pipeline of the unit was calculated when replacing steel pipes with composite ones. It is proved that the use of the developed technology to hydrate formation control in the reduction gas line of the reduction unit provides a more rational use of the energy of the natural gas stream. The preservation of the temperature of the transported energy carrier in the future will allow the use of the stored heat for the needs of the station or for the needs of consumers.

Investigation of the frequency of free vibrations for pipelines with different physical and mechanical properties of the material

This paper raises the question of a new approach to the dynamic calculation of thin-walled underground pipelines of large diameter, which is based on the application of the Vlasov-Novozhilov half-time theory of medium-bend shells, which ignores the M1 moments that bend the cylindrical shell in the longitudinal direction, since they are much smaller than the M2 moments that bend it in the transverse direction. The resolving equation for this approach is a homogeneous 4th-order differential equation that uses two boundary conditions at each end to solve it. The resulting equation takes into account the parameter of the longitudinal force, the value of the internal pressure, the coefficient of elastic resistance of the soil, the parameter of thinness, as well as the attached mass of the soil. Based on the data obtained from the derived formulas, the frequency characteristics of thin-walled underground pipelines of large diameter with different physical and mechanical properties are determined depending on the length of the element, as well as ground conditions. It is established that the minimum frequencies for the shell form of vibrations in various ground conditions are realized only for steel pipes, and for polyethylene and fiberglass pipes, depending on the coefficient of elastic resistance of the soil, they can be realized both in the rod and shell form. At the same time, using a dynamic stability criterion, derived expressions to determine the critical external pressure, taking into account the pipe length and the number of half waves in the cross section in which there is a constructive denial of the pipeline. Based on this expression, a formula for determining the critical depth of laying for thin-walled pipelines is obtained.

New information about the mechanism of oil displacement from productive reservoirs using flow control technologies

The article is devoted to improving the efficiency of methods application to increase oil recovery of deposits that are at the final stage of development. This stage is characterized by a high degree of waterlogging of reservoirs and extracted products. From a wide range of chemical methods for increasing oil recovery in Russian oil deposits, flow-regulating (flow-deflecting) technologies have become widespread. The article analyzes the results of purposeful use of thickened water for the completion of reserves of already flooded sandstone layers. Experimental studies were performed on two specially created five-point elements in the experimental sections of the Romashkinskoye deposit. To monitor the process of low-viscosity and high-viscosity oil displacement the following methods were used: a) intake, monitoring and production wells, in which the interval of productive horizons are lined with fiberglass pipes; b) method of high-frequency resistivity (technology of "VNIIneftepromgeophysics" Institute). The studies performed in the monitoring mode showed that, along with the increase in reservoir coverage by flooding at the macro level, there is also a displacement of part of the capillary-trapped oil in the already flooded layers’ intervals, that is, at the level of micro-uniformity of the porous medium. The paper concludes on the effectiveness of using flow-regulating technologies in conditions of high water availability of development objects.

Studying the Curing Conditions of Unsaturated Polyesters from Secondary Polyethylene Terephthalate Alcoholysis Products

The technological properties of the curing conditions for unsaturated polyesters synthesized on the basis of the alcoholysis products of secondary polyethylene terephthalate and unsaturated polyesters used in the production of fiberglass pipes were studied. It is shown that unsaturated polyesters synthesized on the basis of alcoholysis products can completely replace imported resins of grades 196 and 196A in the production of fiberglass pipes.